By his proper name Cuumian, Cuimíne, Cumméne, variously transcribed CuiminusCuminus-Cummianus, he is not easily identified. He was perhaps abbot at Durrow in S Ireland but also thought to have been the abbot Cummeneus Albus at Iona this does not seem probable. He could also be identified with Cuimmíne Fota Cummianus Longus, who died in 661. His name was absorbed into the legendary cycle of Guaire Aidni, which makes him a globe-trotter. He could have been the abbot of Clonfert ca. 590–662. Some texts can be listed under Cummian’s name: the letter addressed to abbot Segienus of Iona and the hermit Beccanus Beccán, to induce the Celtic churches to adopt the Roman date of Easter De controversia paschali, written ca. 632633; he insists on church unity regarding the date of the Easter celebration. To him, or to another Cummian a monk in Ireland who later lived at Bobbio in the 1st half of the 8th c., is attributed a Liber poenitentialis or Poenitentiale seu Iudicia Cummeani, in which the author reviews the major vices and their penances.
The hymn Celebra, Iuda, in sanctorum apostolorum, attributed to him, is an evocation in 22 distichs of the names of the apostles, evangelists and some other saints. Also attributed to him is a Commentarius in evangelium secundum Marcum CPL 632; BCLL 345 and the De figuris apostolorum BCLL 292. CPL 1136, 1882, 2310; BCLL 289; De controversia paschali: PL 87, 969-978; Poenitentiale Cummeani: PL 87, 978-998: PLS, 4, 2039- 2051; Hymn Celebra, Iuda: PLS, 4, 2051-2052; L. Bieler, The Irish Penitentials, Dublin 1963, 108-135 text and Eng. version; Dreves u. Blume, Anal. hymnica M. Aevi, Leipzig, 51 1908 308-311; J.F. Kenney, The Sources for the Early History of Ireland I, New York 1929, n. 73, 93; T. Oakley, A Great Penitential and Its Authorship: Romanic Review 25 1934 25-33; J.E.L. Oulton, The Epistle of Cummian “De controversia paschali”: SP 1 = TU 63 1957 128-133; BS IV, 393; D. O Cróinín, A Seventh-Century Irish Computus from the Circle of Cummianus: PRIA 82 C 1982 405-430; W. Walsh – D. O Cróinín ed. and tr., Cummian’s Letter De controversia Paschali and the De ratione conputandi Studies and Texts 86, Toronto 1988; Patrologia IV, 457- 461; LACL 167-168.